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  • 1.
    Hruzova, Katerina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Patel, Alok
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Masák, Jan
    Department of Biotechnology, University of Chemistry and Technology Prague, Prague, Czech Republic.
    Maťátková, Olga
    Department of Biotechnology, University of Chemistry and Technology Prague, Prague, Czech Republic.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    A novel approach for the production of green biosurfactant from Pseudomonas aeruginosa using renewable forest biomass2020Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 711, artikkel-id 135099Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The rising demand for surfactants by the pharmaceuticals and cosmetic industries has generated vast amounts of petroleum-based synthetic surfactants, which are often toxic and non-degradable. Owing to their low toxicity, stability in extreme conditions, and biodegradability, biosurfactants could represent a sustainable alternative. The present study aimed to maximize the production of rhamnolipids (RL) from Pseudomonas aeruginosa by optimizing glucose concentration, temperature, and C/N and C/P ratios. After 96 h of cultivation at 37 °C, the final RL concentration was 4.18 ± 0.19 g/L with a final yield of 0.214 ± 0.010 g/gglucose when pure glucose was used as a carbon source. At present, the main obstacle towards commercialization of RL production is economic sustainability, due to the high cost of downstream processes and media components. For this reason, a renewable source such as wood hydrolysates (from birch and spruce woodchips) was examined here as a possible source of glucose for RL production. Both hydrolysates proved to be adequate, resulting in 2.34 ± 0.17 and 2.31 ± 0.10 g/L of RL, respectively, and corresponding yields of 0.081 ± 0.006 and 0.089 ± 0.004 g/gsugar after 96 h. These results demonstrate the potential of using renewable biomass for the production of biosurfactants and, to the best of our knowledge, they constitute the first report on the use of wood hydrolysates for RL production.

  • 2.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Antonopoulou, Io
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Enman, Josefine
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Lipids detection and quantification in oleaginous microorganisms: an overview of the current state of the art2019Inngår i: BMC Chemical Engineering, ISSN 2524-4175, Vol. 1, artikkel-id 13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oleaginous microorganisms are among the most promising feedstocks for the production of lipids for biofuels and oleochemicals. Lipids are synthesized in intracellular compartments in the form of lipid droplets. Therefore, their qualitative and quantitative analysis requires an initial pretreatment step that allows their extraction. Lipid extraction techniques vary with the type of microorganism but, in general, the presence of an outer membrane or cell wall limits their recovery. This review discusses the various types of oleaginous microorganisms, their lipid accumulating capabilities, lipid extraction techniques, and the pretreatment of cellular biomass for enhanced lipid recovery. Conventional methods for lipid quantification include gravimetric and chromatographic approaches; whereas non-conventional methods are based on infrared, Raman, nuclear magnetic resonance, and fluorescence spectroscopic analysis. Recent advances in these methods, their limitations, and fields of application are discussed, with the aim of providing a guide for selecting the best method or combination of methods for lipid quantification.

  • 3.
    Patel, Alok
    et al.
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), India.
    Arora, Neha
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), India.
    Mehtani, Juhi
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), India.
    Pruthi, Vikas
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), India.
    Pruthi, Parul A.
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), India.
    Assessment of fuel properties on the basis of fatty acid profiles of oleaginous yeast for potential biodiesel production2017Inngår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 77, s. 604-616Artikkel i tidsskrift (Fagfellevurdert)
  • 4.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee.
    Arora, Neha
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee.
    Pruthi, Vikas
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee.
    Pruthi, Parul A.
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee.
    A novel rapid ultrasonication-microwave treatment for total lipid extraction from wet oleaginous yeast biomass for sustainable biodiesel production2019Inngår i: Ultrasonics sonochemistry, ISSN 1350-4177, E-ISSN 1873-2828, Vol. 51, s. 504-516Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oleaginous yeasts have emerged as a sustainable source of renewable oils for liquid biofuels. However, biodiesel production from them has few constraints with respect to their cell disruption and lipid extraction techniques. The lipid extraction from oleaginous yeasts commonly includes dewatering and drying of cell biomass, which requires energy and time. The aim of this work was to establish a process for the lipid extraction techniques from wet biomass applying acid catalyzed hot water, microwave, rapid ultrasonication-microwave treatment together with conventional Bligh and Dyer method. In the wake of testing all procedures, it was revealed that rapid ultrasonication-microwave treatment has great potential to give high lipid content (70.86 % w/w) on the cell dry weight basis. The lipid profile after treatment showed the presence of appropriate quantities of saturated (10.39 ± 0.15%), monounsaturated (76.55 ± 0.19%) and polyunsaturated fatty acids (11.49 ± 0.23%) which further improves biodiesel quality compared to the rest of methods. To the best of our knowledge, this is the first report of using rapid ultrasonication-microwave treatment for the lipid extraction from wet oleaginous yeast biomass in the literature.

  • 5.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hruzova, Katerina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Sustainable biorefinery concept for biofuel production through holistic volarization of food waste2019Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 294, artikkel-id 122247Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to utilize the whole food waste in two stages. In the first stage, the carbohydrate and protein fractions of food waste recovered after enzymatic hydrolysis was used to cultivate heterotrophic microalgae, resulting in biomass yield of 0.346 ± 0.09 g/gsugars and lipid yield of 0.216 ± 0.06 g/gsugars. In the second stage, oil (14.15% w/w) was extracted from food waste after hydrolysis and converted to biodiesel by a two-step transesterification reaction that generated 135.8 g/kgfood waste of fatty acid methyl esters and 13.8 g/kgfood waste of crude glycerol. Finally, crude glycerol obtained from both processes was used at 20 g/L to cultivate heterotrophic microalgae, resulting in a cell dry weight and total lipid concentration of 6.23 g/L and 2.91 g/L, respectively. A total 248.21 g of fatty acid methyl esters were obtained from the 1 kg of food waste through this integrated process.

  • 6.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    A comparative study on de novo and ex novo lipid fermentation by oleaginous yeast using glucose and sonicated waste cooking oil2019Inngår i: Ultrasonics sonochemistry, ISSN 1350-4177, E-ISSN 1873-2828, Vol. 52, s. 364-374Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There are only a few reports available about the assimilation of hydrophobic substrates by microorganisms, however, it is well known that oleaginous microorganisms are capable of utilizing both hydrophilic and hydrophobic substrates and accumulate lipids via two different pathways namely de novo and ex novo lipid synthesis, respectively. In the present study, an oleaginous yeast, Cryptococcus curvatus, was investigated for its potentials to utilize a waste substrate of hydrophobic nature (waste cooking oil – WCO) and compared with its ability to utilize a hydrophilic carbon source (glucose). To facilitate the utilization of WCO by C. curvatus, the broth was sonicated to form a stable oil-in-water emulsion without adding any emulsifier, which was then compared with WCO samples without any ultrasound treatment (unsonicated) for the yeast cultivation. Ultrasonication reduces the size of hydrophobic substrates and improves their miscibility in an aqueous broth making them easily assimilated by oleaginous yeast. Under de novo lipid fermentation, the yeast synthesized 9.93 ± 0.84 g/L of cell dry weight and 5.23 ± 0.49 g/L lipids (lipid content of 52.66 ± 0.93% w/w) when cultivated on 40 g/L of glucose (C/N ratio of 40). The amount of cell dry weight, lipid concentration, and lipid content were considerably higher during the ex novo lipid synthesis. More specifically, the highest lipid content achieved was 70.13 ± 1.65% w/w with a corresponding dry cell weight and lipid concentration of 18.62 ± 0.76 g/L and 13.06 ± 0.92 g/L respectively, when grown on 20 g/L sonicated WCO. The highest lipid concentration, however, was observed when the yeast was cultivated on 40 g/L sonicated WCO. Under these conditions, 20.34 g/L lipids were produced with a lipid content of 57.05% w/w. On the other hand, lipid production with unsonicated WCO was significant lower, reaching 11.16 ± 1.02 g/L (69.14 ± 1.34% w/w of lipid content) and 12.21 ± 1.34 g/L (47.39 ± 1.67% w/w of lipid content) for 20 g/L and 40 g/L of WCO, respectively. This underpins the significance of the sonication treatment, especially at elevated WCO concentrations, to improve the accessibility of the yeast to the WCO. Sonication treatment that was used in this study assisted the utilization of WCO without the need to add emulsifiers, thus reducing the need for chemicals and in turn has a positive impact on the production costs. The microbial lipids produced presented a different fatty acid composition compared to the WCO, making them more suitable for biodiesel production as suggested by the theoretical estimation of the biodiesel properties.

  • 7.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hruzova, Katerina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Biosynthesis of Nutraceutical Fatty Acids by the Oleaginous Marine Microalgae Phaeodactylum tricornutum Utilizing Hydrolysates from Organosolv-Pretreated Birch and Spruce Biomass2019Inngår i: Marine Drugs, ISSN 1660-3397, E-ISSN 1660-3397, Vol. 17, nr 12, artikkel-id 119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polyunsaturated fatty acids (PUFAs) are essential for human function, however they have to be provided through the diet. As their production from fish oil is environmentally unsustainable, there is demand for new sources of PUFAs. The aim of the present work was to establish the microalgal platform to produce nutraceutical-value PUFAs from forest biomass. To this end, the growth of Phaeodactylum tricornutum on birch and spruce hydrolysates was compared to autotrophic cultivation and glucose synthetic media. Total lipid generated by P. tricornutum grown mixotrophically on glucose, birch, and spruce hydrolysates was 1.21, 1.26, and 1.29 g/L, respectively. The highest eicosapentaenoic acid (EPA) production (256 mg/L) and productivity (19.69 mg/L/d) were observed on spruce hydrolysates. These values were considerably higher than those obtained from the cultivation without glucose (79.80 mg/L and 6.14 mg/L/d, respectively) and also from the photoautotrophic cultivation (26.86 mg/L and 2.44 mg/L/d, respectively). To the best of our knowledge, this is the first report describing the use of forest biomass as raw material for EPA and docosapentaenoic acid (DHA) production.

  • 8.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee, Uttarakhand, India .
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Pruthi, Parul A
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee, Uttarakhand, India .
    Pruthi, Vikas
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee, Uttarakhand, India .
    Potential of aquatic oomycete as a novel feedstock for microbial oil grown on waste sugarcane bagasse2018Inngår i: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 25, nr 33, s. 33443-33454Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biodiesel production from vegetable oils is not sustainable and economical due to the food crisis worldwide. The development of a cost-effective non-edible feedstock is essential. In this study, we proposed to use aquatic oomycetes for microbial oils, which are cellulolytic fungus-like filamentous eukaryotic microorganisms, commonly known as water molds. They differ from true fungi as cellulose is present in their cell wall and chitin is absent. They show parasitic as well as saprophytic nature and have great potential to utilize decaying animal and plant debris in freshwater habitats. To study the triacylglycerol (TAG) accumulation in the aquatic oomycetes, the isolated water mold Achlya diffusa was cultivated under semi-solid-state conditions on waste sugarcane bagasse, which was compared with the cultivation in Czapek (DOX) medium. A. diffusa grown on waste sugarcane bagasse showed large lipid droplets in its cellular compartment and synthesized 124.03 ± 1.93 mg/gds cell dry weight with 50.26 ± 1.76% w/w lipid content. The cell dry weight and lipid content of this water mold decreased to 89.54 ± 1.21 mg/gds and 38.82% w/w, respectively, when cultivated on standard medium Czapek-Dox agar (CDA). For the fatty acid profile of A. diffusa grown in sugarcane bagasse and CDA, in situ transesterification (IST) and indirect transesterification (IDT) approaches were evaluated. The lipid profile of this mold revealed the presence of C12:0, C14:0, C16:0, C18:0, C18:1, C18:2, C20:0, and C21:0 fatty acids, which is similar to vegetable oils. The biodiesel properties of the lipids obtained from A. diffusa satisfied the limits as determined by international standards ASTM-D6751 and EN-14214 demonstrating its suitability as a fuel for diesel engines.

  • 9.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    A perspective on biotechnological applications of thermophilic microalgae and cyanobacteria2019Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 278, s. 424-434Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The importance of expanding our knowledge on microorganisms derived from extreme environments stems from the development of novel and sustainable technologies for our health, food, and environment. Microalgae and cyanobacteria represent a group of diverse microorganisms that inhabit a wide range of environments, are capable of oxygenic photosynthesis, and form a thick microbial mat even at extreme environments. Studies of thermophilic microorganisms have shown a considerable biotechnological potential due to their optimum growth and metabolisms at high temperatures (≥50 °C), which is supported by their thermostable enzymes. Microalgal and cyanobacterial communities present in high-temperature ecosystems account for a large part of the total ecosystem biomass and productivity, and can be exploited to generate several value-added products of agricultural, pharmaceutical, nutraceutical, and industrial relevance. This review provides an overview on the current status of biotechnological applications of thermophilic microalgae and cyanobacteria, with an outlook on the challenges and future prospects.

  • 10.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Heterotrophic cultivation of Auxenochlorella protothecoides using forest biomass as a feedstock for sustainable biodiesel production2018Inngår i: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 11, nr 1, artikkel-id 169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background

    The aim of this work was to establish a process for the heterotrophic growth of green microalgae using forest biomass hydrolysates. To provide a carbon source for the growth of the green microalgae, two forest biomasses (Norway spruce and silver birch) were pretreated with a hybrid organosolv-steam explosion method, resulting in inhibitor-free pretreated solids with a high cellulose content of 77.9% w/w (birch) and 72% w/w (spruce). Pretreated solids were hydrolyzed using commercial cellulolytic enzymes to produce hydrolysate for the culture of algae.

    Results

    The heterotrophic growth of A. protothecoides was assessed using synthetic medium with glucose as carbon source, where the effect of sugar concentration and the carbon-to-nitrogen ratio were optimized, resulting in accumulation of lipids at 5.42 ± 0.32 g/L (64.52 ± 0.53% lipid content) after 5 days of culture on glucose at 20 g/L. The use of birch and spruce hydrolysates was favorable for the growth and lipid accumulation of the algae, resulting in lipid production of 5.65 ± 0.21 g/L (66 ± 0.33% lipid content) and 5.28 ± 0.17 g/L (63.08 ± 0.71% lipid content) when grown on birch and spruce, respectively, after only 120 h of cultivation.

    Conclusions

    To the best of our knowledge, this is the first report of using organosolv pretreated wood biomass hydrolysates for the growth and lipid production of microalgae in the literature. The pretreatment process used in this study provided high saccharification of biomass without the presence of inhibitors. Moreover, the lipid profile of this microalga showed similar contents to vegetable oils which improve the biodiesel properties.

  • 11.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mikes, Fabio
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Bühler, Saskja
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Valorization of Brewers’ Spent Grain for the Production of Lipids by Oleaginous Yeast2018Inngår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 23, nr 12, artikkel-id 3052Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Brewers’ spent grain (BSG) accounts for 85% of the total amount of by-products generated by the brewing industries. BSG is a lignocellulosic biomass that is rich in proteins, lipids, minerals, and vitamins. In the present study, BSG was subjected to pretreatment by two different methods (microwave assisted alkaline pretreatment and organosolv) and was evaluated for the liberation of glucose and xylose during enzymatic saccharification trials. The highest amount of glucose (46.45 ± 1.43 g/L) and xylose (25.15 ± 1.36 g/L) were observed after enzymatic saccharification of the organosolv pretreated BSG. The glucose and xylose yield for the microwave assisted alkaline pretreated BSG were 34.86 ± 1.27 g/L and 16.54 ± 2.1 g/L, respectively. The hydrolysates from the organosolv pretreated BSG were used as substrate for the cultivation of the oleaginous yeast Rhodosporidium toruloides, aiming to produce microbial lipids. The yeast synthesized as high as 18.44 ± 0.96 g/L of cell dry weight and 10.41 ± 0.34 g/L lipids (lipid content of 56.45 ± 0.76%) when cultivated on BSG hydrolysate with a C/N ratio of 500. The cell dry weight, total lipid concentration and lipid content were higher compared to the results obtained when grown on synthetic media containing glucose, xylose or mixture of glucose and xylose. To the best of our knowledge, this is the first report using hydrolysates of organosolv pretreated BSG for the growth and lipid production of oleaginous yeast in literature. The lipid profile of this oleaginous yeast showed similar fatty acid contents to vegetable oils, which can result in good biodiesel properties of the produced biodiesel

  • 12.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mikes, Fabio
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    An Overview of Current Pretreatment Methods Used to Improve Lipid Extraction from Oleaginous Microorganisms2018Inngår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 23, nr 7, artikkel-id 1562Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microbial oils, obtained from oleaginous microorganisms are an emerging source of commercially valuable chemicals ranging from pharmaceuticals to the petroleum industry. In petroleum biorefineries, the microbial biomass has become a sustainable source of renewable biofuels. Biodiesel is mainly produced from oils obtained from oleaginous microorganisms involving various upstream and downstream processes, such as cultivation, harvesting, lipid extraction, and transesterification. Among them, lipid extraction is a crucial step for the process and it represents an important bottleneck for the commercial scale production of biodiesel. Lipids are synthesized in the cellular compartment of oleaginous microorganisms in the form of lipid droplets, so it is necessary to disrupt the cells prior to lipid extraction in order to improve the extraction yields. Various mechanical, chemical and physicochemical pretreatment methods are employed to disintegrate the cellular membrane of oleaginous microorganisms. The objective of the present review article is to evaluate the various pretreatment methods for efficient lipid extraction from the oleaginous cellular biomass available to date, as well as to discuss their advantages and disadvantages, including their effect on the lipid yield. The discussed mechanical pretreatment methods are oil expeller, bead milling, ultrasonication, microwave, high-speed and high-pressure homogenizer, laser, autoclaving, pulsed electric field, and non-mechanical methods, such as enzymatic treatment, including various emerging cell disruption techniques.

  • 13.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee, Uttarakhand, India.
    Pruthi, Vikas
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee, Uttarakhand, India;iofuel Laboratory, Centre for Transportation Systems, Indian Institute of Technology Roorkee (IIT-R), Roorkee, Uttarakhand, India.
    Pruthi, Parul A.
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee, Uttarakhand, India.
    Innovative screening approach for the identification of triacylglycerol accumulating oleaginous strains2019Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 135, s. 936-944Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Currently, triacylglycerides (TAG) accumulation in the form of lipid droplets (LDs) in oleaginous microorganisms is of immense importance due to their ability to get transesterified into value-added products in the form of biodiesel. Hence, in order to search for oleaginous microorganisms having high lipid content among a wide range of samples from different niches, there is a compulsive need to develop simple, reliable and rapid methods for screening of TAG accumulating strains. Conventional methods require multistep processes for the isolation, cultivation, extraction and estimation of lipids to identify oleagenic strains. To overcome these challenges, we are proposing an easy, live cellimaging technique for the estimation of lipids via visualization of TAG accumulation in probable strains at the single cell level that gives real-time monitoring of intracellular lipid accumulation in yeasts. In this screening technique, only 100 μl of specific neutral lipid accumulating medium was used to grow the isolated culture in the microtiter plate. The harvested cells were stained with LipidTOX™ Green and visualized by a LED based digital inverted fluorescence microscope. Among 446 yeast colonies screened, maximum lipid producing yeast strains Rhodosporidium kratochvilovae HIMPA1 and Rhodotorula minuta,having supersized lipid body of 5.05 ± 0.87 μm and 4.46 ± 0.61 μm, respectively, were identified as potential candidates for biodiesel production. To the best of our knowledge, this is the first report of using LipidTOX™ Green for the staining of lipid droplets present in yeast cells as per the literature.

  • 14.
    Patel, Alok
    et al.
    Molecular Microbiology Laboratory, Department of Biotechnology, Indian Institute of Technology Roorkee (IIT-R), India.
    Pruthi, Vikas
    Molecular Microbiology Laboratory, Department of Biotechnology, Indian Institute of Technology Roorkee (IIT-R), India.
    Pruthi, Parul A.
    Molecular Microbiology Laboratory, Department of Biotechnology, Indian Institute of Technology Roorkee (IIT-R), India.
    Synchronized nutrient stress conditions trigger the diversion of CDP-DG pathway of phospholipids synthesis towards de novo TAG synthesis in oleaginous yeast escalating biodiesel production2017Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 139, s. 962-974Artikkel i tidsskrift (Fagfellevurdert)
  • 15.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Simultaneous production of DHA and squalene from Aurantiochytrium sp. grown on forest biomass hydrolysates2019Inngår i: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 12, nr 1, artikkel-id 255Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background

    Recent evidence points to the nutritional importance of docosahexaenoic acid (DHA) in the human diet. Thraustochytrids are heterotrophic marine oleaginous microorganisms capable of synthesizing high amounts of DHA, as well as other nutraceutical compounds such as squalene, in their cellular compartment. Squalene is a natural triterpene and an important biosynthetic precursor to all human steroids. It has a wide range of applications in the cosmetic and pharmaceutical industries, with benefits that include boosting immunity and antioxidant activity. Apart from its nutritional quality, it can also be utilized for high-grade bio-jet fuel by catalytic conversion.

    Results

    In the present study, the potential of thraustochytrid strain Aurantiochytrium sp. T66 to produce DHA and squalene was evaluated. When the strain was cultivated on organosolv-pretreated birch hydrolysate (30 g/L glucose) in flask, it resulted in 10.39 g/L of cell dry weight and 4.98 g/L of total lipids, of which 25.98% was DHA. In contrast, when the strain was grown in a bioreactor, cell dry weight, total lipid, and DHA increased to 11.24 g/L, 5.90 g/L, and 35.76%, respectively. The maximum squalene yield was 69.31 mg/gCDW (0.72 g/L) when the strain was cultivated in flask, but it increased to 88.47 mg/gCDW (1.0 g/L), when cultivation shifted to a bioreactor.

    Conclusions

    This is the first report demonstrating the utilization of low cost non-edible lignocellulosic feedstock to cultivate the marine oleaginous microorganism Aurantiochytrium sp. for the production of nutraceutical vital compounds. Owing to the simultaneous generation of DHA and squalene, the strain is suitable for industrial-scale production of nutraceuticals.

  • 16.
    Patel, Alok
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee, India.
    Sartaj, K.
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee, India.
    Pruthi, P.A.
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee, India.
    Pruthi, V.
    Molecular Microbiology Laboratory, Biotechnology Department, Indian Institute of Technology Roorkee (IIT-R), Roorkee, India.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Utilization of Clarified Butter Sediment Waste as a Feedstock for Cost-Effective Production of Biodiesel2019Inngår i: Foods, E-ISSN 2304-8158, Vol. 8, nr 7, artikkel-id 234Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The rising demand and cost of fossil fuels (diesel and gasoline), together with the need for sustainable, alternative, and renewable energy sources have increased the interest for biomass-based fuels such as biodiesel. Among renewable sources of biofuels, biodiesel is particularly attractive as it can be used in conventional diesel engines without any modification. Oleaginous yeasts are excellent oil producers that can grow easily on various types of hydrophilic and hydrophobic waste streams that are used as feedstock for single cell oils and subsequently biodiesel production. In this study, cultivation of Rhodosporidium kratochvilovae on a hydrophobic waste (clarified butter sediment waste medium (CBM)) resulted in considerably high lipid accumulation (70.74% w/w). Maximum cell dry weight and total lipid production were 15.52 g/L and 10.98 g/L, respectively, following cultivation in CBM for 144 h. Neutral lipids were found to accumulate in the lipid bodies of cells, as visualized by BODIPY staining and fluorescence microscopy. Cells grown in CBM showed large and dispersed lipid droplets in the intracellular compartment. The fatty acid profile of biodiesel obtained after transesterification was analyzed by gas chromatography-mass spectrometry (GC–MS), while its quality was determined to comply with ASTM 6751 and EN 14214 international standards. Hence, clarified sediment waste can be exploited as a cost-effective renewable feedstock for biodiesel production. 

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